The term bats in the belfry is a proverbial expression that refers to chaotic situations and behavior.
Similar to bats, who often inhabit belfries as a living space, people sometimes act erratically when disturbed. The expression is often used about individuals who exhibit behavior similar to a cauldron of disrupted bats.
The term originates from 19th and 20th century America, when bats inhabiting a church’s belfry (the part of the church containing the bell) was a common occurrence.
The first recorded instance of bats in a belfry appearing in print dates back to the year 1900, in The Newark Daily Advocate.
During the first two decades of the 20th century, the proverbial expression was very popular in literary circles, and was featured in many poems and novels at the time. Eventually it lost its popularity by the end of the 1910s.
In 1942 and 1960, two U.S. movies (independent from each other) were given the title Bats in The Belfry.
The band Dispatch also named one of their songs based on the expression in 1996.